(HOTAIR) Now that Rick Santorum has withdrawn from the Republican nomination race, Mitt Romney’s challenge will be to unify the party quickly. He got plenty of help last night from Hilary Rosen, who attacked Ann Romney for being a stay-at-home mom and created a massive reaction among conservatives rallying to defend her. Today, two key conservative groups announced endorsements for Romney in a move that may help stoke momentum for the all-but-certain nominee.